1. Field of the Invention
The present invention relates to a measurement element for determination of a flow rate of a fluid which is flowing around the measurement element, using a conductor for carrying an electromagnetic wave along its longitudinal extent and at least one electrical heating element, which is arranged adjacent to the conductor. The invention also relates to a technical steam machine having a measurement element according to the invention, and to a method for determination of a flow rate of a fluid.
2. Description of the Related Art
A large number of flowmeters are known from the related art. By way of example, volume flowmeters are used to determine a flow in which the amount of fluid flowing through a predetermined line cross section in a specific time is measured. For this purpose, volume flowmeters have two oval wheels which are arranged in a measurement chamber and roll against one another, with the flow rate being determined from the rotation speed. Furthermore, effective pressure measurements are known, in which a predetermined constriction is provided in a line cross section and the flow rate is determined from a pressure difference upstream of the constriction and in the constriction. Inductive or ultrasound flowmeters are also known.
The already known methods have the disadvantage that their usage capabilities are restricted, particularly when access to a flow channel is difficult, or when stringent requirements have to be satisfied with regard to the physical and/or chemical load. The measurement elements from the related art are also inaccurate for large flow cross sections since they allow only a point measurement and cannot detect flow profile discrepancies transversely with respect to the flow direction.
Furthermore, the known measurement methods for determination of flow rates are largely unsuitable for sufficiently accurately determining the flow rate and/or the distribution of the flow rate transversely with respect to the flow direction in a flow channel of a technical steam machine. In particular, the determination process is made more difficult by the fact that the materials which can be used in the flow channel of a technical steam machine are subject to stringent requirements with regard to the chemical and/or physical load. Thermocouple arrangements of a complex design are therefore used in gas turbines in order to determine the flow rate at at least a number of predetermined points. This is based on the principle that the flow in the flow channel correspondingly cools down a heated thermocouple.